Put off means to divest yourself of something, to take it off. Paul is using the simplest of terms to illustrate what we must do in the realm of thought, of the attitudes of life. We must reject those basic assumptions that have caused our trouble—putting them off, rejecting them, divesting ourselves of them—just as you would put off your dirty clothes. We must do this because the corruption of life comes from these wrong attitudes.

The first step in experiencing what God intends for us is to recognize that. Put off the old. That is the first step. The other is to recognize the wonderful possibilities of the new life. In the NIV translation the phrase, to be made new in the attitude of your minds, (v 23) you see the fundamental difference between a Christian and a non-Christian. It is true that non-Christians sometimes realize that things are wrong in their lives, and so they change them. But they change the outer form, but the problem remains basically the same: they are still dead in their sin.